@Matt Rosenbohm I have had this same internal conversation more and more frequently lately .
The math will always indicate that buying more is better - more appreciation, higher rent rolls, easier to grow net worth, etc. So getting cash out and buying more is the easy spreadsheet answer. But because you asked the question and considered option number 3 there is something in your gut that says it may not be what is best for you.
Assuming you plan to stay invested in Northern Co - I think you will find that once you start looking to buy more rentals that the deals don't perform as well as what you have already purchased with out increasing your overall debt for down payments. If you are going to 1031 - explore a reverse exchange - in a competitive market it allows you to be more selective and not forced by the timeline to buy a marginal deal.
Going to a bigger apartment deal (assuming in CO) are trading at such low cap rates and in a raising rate environment isn't that attractive to me. I have preferred a larger portfolio of 1-4 units - easier to liquidate if you need to sell just one building.
Option 3 isn't out of the question - sure it doesn't provide the highest cash on cash or return on equity - but it does provide easy steady income for the future. I am paying off properties now - once I achieved the monthly gross cash flow I wanted it makes sense to me to preserve it and take my foot off the gas on acquisition.
One last thought - You mentioned not spending a lot of time on your portfolio until recently - I was guilty of the same and found that if I more effectively manage the properties I already own - I was better off than buying additional units.
Just one persons opinion - good luck!